Internal combustion engine

ABSTRACT

The invention relates to an internal combustion engine of the type wherein there is associated with each working cylinder an additional cylinder communicating with the working cylinder and containing a piston which displaces a smaller volume than that of the working cylinder and co-operates with a crankshaft positively connected with the crankshaft of the working piston, which two crankshafts can be offset angularly relatively to one another, and in the said engine the frequency of rotation of the crankshaft co-operating with the piston of the additional cylinder is more than twice that of the crankshaft co-operating with the piston of the working cylinder and is preferably 3 times as great.

United States Patent Dutry et al.

INTERNAL COMBUSTION ENGINE Inventors: Jean Ernest Dutry, Steenweg op Brussel, 340, 1900 Overijse; Alfred Hubert Feyens, Avenue Prince Baudouin 9, 1150 Brussels, both of Belgium Filed: July 16, 1973 Appl. No.: 379,816

US. Cl. 123/51R, 123/51 A, 123/51 B,

123/51 BA, 123/78 R, 123/78 A Int. Cl. F02b 75/04 [58] Field of Search 123/78 R, 78 A, 51 BA, 123/51 BB, 51 R, 51 A, 51 AA References Cited UNITED STATES PATENTS 1/1931 Woolson 123/51 A [111 3,868,931 [4 1 Mar. 4, 1975 6/1933 Wolf 123/51 AA 5/1970 Fiaga-Fernbrugg 123/51 A [57] ABSTRACT The invention relates to an internal combustion engine of the type wherein there is associated with each working cylinder an additional cylinder communicating with the working cylinder and containing a piston which displaces a smaller volume than that of the working cylinder and co-operates with a crankshaft positively connected with the crankshaft of the working piston, which two crankshafts can be offset angularly relatively to one another, and in the said engine the frequency of rotation of the crankshaft cooperating with the piston of the additional cylinder is more than twice that of the crankshaft co-operating with the piston of the working cylinder and is preferably 3 times as great.

6 Claims, 2 Drawing Figures PATENTEDIAR 4191s 3.868.931 sum 2 a! g I. INTERNAL COMBUSTION ENGINE The invention relates to an internal combustion engine capable of using fluid fuels which contain no additives or few additives and of producing combustion gases which are poor in toxic substances.

It is well known that in most internal combustion engines a pattern of variation is imposed on the volume of a space bounded by the walls of a cylinder and a piston, usually several cylinders with pistons, whereas valves or ports unmasked by the pistons or by slide valves control the admissionand/or discharge of the gases.

The efficiency of the heat cycle is chiefly influenced by the compression ratio but the variations during the cycle of the linear speed of the piston operated by a connecting rod and crank system are such that the compression ratio which can be used is limited by the more or less explosive character of the fuel-air mixture used.

For engines with preliminary carburetting and controlled ignition it is necessary to prepare knock-free fuels (a quality characterised by the octane number) at considerable cost in order to be able to increase the compression ratio, but this remains limited. In most cases this requires incorporating in the fuel harmful compounds which in the end are dispersed in the atmosphere. Furthermore, when such an engine is idling, combustion is incomplete and a considerable quantity of harmful gases is discharged into the atmosphere. Because of the great and ever-increasing number of vehicles in use, these discharges of harmful gases and compounds tend to exceed the acceptable level. In most countries, regulations will very shortly have to set out strict limits on the discharge of polluting substances.

In the case of compression-ignition engines, the difficulties are of a different kind but also are due to characteristics of the progress of the volume controlled by the connecting rod and crank system. Here, the fuel has to be prepared for rapid ignition (a quality characterised by the cetane number) as soon as injection begins. This is necessary because delaying the start of the combustion process gives an explosive character to the propagation of the flame, and also since the sudden increase in pressure would be applied at an unfavourable instant in the movement of the connecting rod and crank system.

The requirements of internal combustion engines and the increase in the number of such engines makes the task of the oil and petrol companies more and more dif ficult, having to meet conflicting requirements on the one hand for fuel having a high octane number for engines with preliminary carburetting, and on the other hand fuel with a high cetane number for compressionignition engines.

Up to the present time it has been attempted without success to provide internal combustion engines wherein the pattern of change in the volume of a cylinder is such that it is possible to use a fuel which does not contain toxic substances for reducing the tendency to knock, and at the same time ensuring complete combustion with a substantially reduced noise.

More particularly it has been proposed in vain to as sociate with each working cylinder an additional cylinder communicating with the working cylinder and containing a piston which displaces a smaller volume than that of the working cylinder and may cooperate with a crank shaft positively connected with the crankshaft of the working piston. It has also been proposed that the two crankshafts can be offset angularly relatively to one another and that the frequency of rotation of the crankshaft co-operating with the piston of the additional cylinder may be either half or about double that of the crankshaft co-operating with the piston of the working cylinder.

It has now been found according to the present invention that an internal combustion engine satifies to a considerable extent the conditions mentioned hereinbefore when the frequency of the rotational speed of the crankshaft co-operating with the piston of the additional cylinder is greater than twice that of the crankshaft co-operating with the piston of the working cylinder and is preferably 3 times the speed of rotation of the crankshaft co-operating with the piston of the latter cylinder.

The volume displaced by the piston of the additional cylinder is then advantageously between a fifth and a third of that displaced by the piston of the working cylinder and corresponds preferably to a quarter of the volume displaced by the piston of the working cylinder, the crankshaft co-operating with the piston of the working cylinder being given a lead relatively to that which co-operates with the piston of the additional cylinder to the extent of an angle of between 15 and 45, advantageously about 30.

In an engine which meets these requirements, the progress of the sum of the volumes relatively to the progress of the volume of the working cylinder is such that during a decompression movement the sum of the volumes reaches its minimum shortly after the crankshaft co-operating with the working cylinder has moved through its upper dead centre, becomes at one given instant identical with the volume of the working cylinder, and then increases in the first portion of this movement more quickly than the volume of the working cylinder, slows down substantially at the beginning of the second portion of the movement, becomes at a given instant a second time identical with the volume of the working cylinder, to increase again more rapidly than the volume of the working cylinder and reach its maximum volume after the crankshaft co-operating with the piston of the working cylinder has moved through its lower dead centre. This long movement cycle of the sum of the volumes promotes combustion and makes it more complete. During a compression movement the sum of the volumes decreases considerably during the first portion of the movement, at a given instant becomes identical with the volume which the working cylinder has, then decreases during the second portion of the movement more slowly than the volume of the working cylinder does and reaches a minimum after the crankshaft co-operating with the piston of the working cylinder has moved through the upper dead centre. As a result there is a compression pressure which first of all increases very slowly, and at the instant when the crankshaft co-operating with the piston of the working cylinder passes through the upper dead centre reaches less than half of the final pressure. This latter does not act on the crankshaft except when the crankshaft is in a suitable working postion, which permits the use of fuels which are not rendered knock-free by harmful additives.

One constructional form of the invention is shown by way of information in the accompanying drawings.

FIG. 1 shows diagrammatically an engine according to the invention, and

FIG. 2 shows the pattern of variation of the sum of the volumes of a working cylinder and an additional.

cylinder.

An internal combustion engine according to the in-. vention comprises one or more working cylinders 1 with a piston 2 co-operating by means of a connecting rod 3 with a crankshaft 4. Each cylinder 1 communicates with an additional cylinder 5 provided with a piston 6 co-operating by means of a connecting rod 7 with a crankshaft 8. The cylinder head common to the two cylinders l and 5 contains a combustion chamber 9. The crankshafts 4 and 8 are connected to one another by positive drive means, for example gearwheels 10 and 11 and intermediate pinions 12.

The two cylinders are shown in FIG. 1 in a coaxial position but it will be apparent that they could be arranged otherwise, for example with parallel axes, especially when it is necessary to provide the space necessary for valves on the common cylinder head.

The frequency of rotation of the crankshaft 8 is preferably three times that of the crankshaft 1 and the volume displaced by the piston 6 is about a quarter of that displaced by the piston 2. The crankshafts 1 and 8 are offset relatively to one another by an angle of about 30, the crankshaft 4 being in advance relatively to the crankshaft 8.

FIG. 2 shows the pattern of variation of the volumes displaced in the cylinders 1 and 5 of an internal combustion engine corresponding to the features indicated hereinbefore. In this illustration the y-axis y-y indicates the volumes displaced and the x-axis x-x the angles of rotation concerning the crankshaft 4 cooperating with the piston 2 of the working cylinder 1. The line 14 corresponds to the volume displaced by the piston 2 and, shown at the other side of the x-axis, the line 15 to that displaced by the piston 6 of the additional cylinder. Disregarding the dead space of the combustion chamber 9, the upper dead centres of the crankshafts 4 and 8 are situated on the x-axis itself, in the case of the crankshaft 4 at angles of 0 and 360, and as regards the crankshaft 8 at angles of 30, 150 and 270, the corresponding lower dead centres being at angles of 1 80 (crankshaft 4) and 90, 210, and 330 (crankshaft 8).

Line 16 represents the sum of the volumes displaced simultaneously by the pistons 2 and 6. This line has its culminating point at 17 representing the maximum volume of the group of two cylinders. This point 17 is reached after the crankshaft'4 has moved beyond its lower dead centre and is situated in a useful working position. The same applies as regards the minimum points 18 and 18' of the line 16, which occur when the crankshaft 4 has moved beyond its upper dead centre.

During a movement of the sum of volumes in the increasing sense (decompression) between the points 18 and 17, the line 16 on two occasions is in contact with the line 14, at the points 19 and 20 (angles of 30 and 150). Between the points 19 and 20, the sum of the volumes increases first of all more sharply than the volume according to the line 14 up to the angle of rotation of 90, and then increases between the angles of 90 and 150 substantially less than the volume indicated by the line 14. From the point 20 the increase in the sum of the volumes is again greater up to the point 17. This particular form of the line 16 between the points 4 l8 and 17 promotes the combustion of the fuel and makes it more complete.

During a reduction movement of the sum ofthe volumes, corresponding to acompression movement between the points 17 and 18', it is found that the line 16 is substantially more considerably inclined than the line 14, which corresponds to a considerable compression at the beginning of the movement when the increase in compression remains without influence on the fuel from the point of view of its resistance to knocking. At the point 21 (angle.270) the line 16 is again in contact with the line 14. From this point onwards, the line 16 is inclined to a smaller extent than the line 14 and thus there is a relatively slowed-down compression up to after the angle of rotation of 330, the minimum volume 18' being reached after the line 16 has intersected the vertical drawn on the angle of 360.

As a result the compression pressure represented by the line 22 for which the auxiliary y-axis y'y' indicates the scale in kg/cm2, is relatively low at the instant when the crankshaft 4 is at its upper dead centre and then increases rapidly to reach a maximum shortly before the crankshaft has reached a rotational movement of 30. It is possible to conclude from this behaviour of the line 22 that an engine according to the present invention permits the use of relatively unsophisticated fuels which are not doped with anti-knock additives likely to pollute the atmosphere.

Of course the invention is not limited to the constructional form described by way of example and it would not constitute a departure from the invention to make modifications thereto.

We claim:

1. Internal combustion engine wherein there is associated with each working cylinder an additional cylinder communicating with the working cylinder and containing a piston which displaces a smaller volume than that of the piston of the working cylinder and cooperates with a crankshaft connected positively with the crankshaft of the piston of the working cylinder, the two crankshafts being angularly offset relatively to one another, characterised in that the frequency of the rotation of the crankshaft co-operating with the piston of the additional cylinder is more than double that of the crankshaft co-operating with the piston of the working cylinder.

2. Internal combustion engine according to claim 1, characterised in that the frequency of rotation of the crankshaft co-operating with the piston of the additional cylinder is three times that of the crankshaft cooperating with the piston of the working cylinder.

3. Internal combustion engine according to claim 2, characterised in that the volume displaced by the piston of the additional cylinder is between a fifth and a third of the volume displaced by the working piston.

4. Internal combustion engine according to claim 3, characterised in that the volume displaced by the piston of the additional cylinder is, about a quarter of the volume displaced by the piston of the working cylinder.

5. Internal combustion engine according to claim 2 characterised in that, when the pistons of both the working and the additional cylinders are simultaneously near their top dead centers, the crankshaft cooperating with the piston of the working cylinder leads relatively to the crankshaft cooperating with the piston of the additional cylinder by an angle of between 15 and 45.

6. Internal combustion engine according to claim 5, characterised in that the crankshaft co-operating with the working cylinder piston leads relatively to the crankshaft co-operating with the piston of the additional cylinder by an angle of about 30. 

1. Internal combustion engine wherein there is associated with each working cylinder an additional cylinder communicating with the working cylinder and containing a piston which displaces a smaller volume than that of the piston of the working cylinder and co-operates with a crankshaft connected positively with the crankshaft of the piston of the working cylinder, the two crankshafts being angularly offset relatively to one another, characterised in that the frequency of the rotation of the crankshaft co-operating with the piston of the additional cylinder is more than double that of the crankshaft co-operating with the piston of the working cylinder.
 2. Internal combustion engine according to claim 1, characterised in that the frequency of rotation of the crankshaft co-operating with the piston of the additional cylinder is three times that of the crankshaft co-operating with the piston of the working cylinder.
 3. Internal combustion engine according to claim 2, characterised in that the volume displaced by the piston of the additional cylinder is between a fifth and a third of the volume displaced by the working piston.
 4. Internal combustion engine according to claim 3, characterised in that the volume displaced by the piston of the additional cylinder is, about a quarter of the volume displaced by the piston of the working cylinder.
 5. Internal combustion engine according to claim 2 characterised in that, when the pistons of both the working and the additional cylinders are simultaneously near their top dead centers, the crankshaft cooperating with the piston of the working cylinder leads relatively to the crankshaft cooperating with the piston of the additional cylinder by an angle of between 15* and 45*.
 6. Internal combustion engine according to claim 5, characterised in that the crankshaft co-operating with the working cylinder piston leads relatively to the crankshaft co-operating with the piston of the additional cylinder by an angle of about 30*. 